The Analytical Core provides routine and non-routine analytical service to the University of lowa research program. The core provides expert staff, equipment, and instrumentation in line with five Aims. Specific Aim 1 is the development of analytical and quality control/assurance standards. In close collaboration with the Synthesis Core, which is responsible for acquiring and archiving individual compound standards and preparing stock solutions, the Analytical Core develops the mathematical methods for congener representation, analyzes single congener solutions for purity assessment and quality control, and tests the prepared standard solutions against certified Standard Reference Materials, including PCB calibration mixtures. Specific Aim 2 is the development of a mixture of PCB congeners for laboratory animal exposure studies. The Analytical Core develop the mathematical methods to design the exposure mixture and tests the prepared mixtures against certified Standard Reference Materials. Specific Aim 3 is the analysis of environmental and laboratory samples for a suite of PCB congener. The Analytical Core will extract and analyze PCBs on a congener-specific basis: 209 congeners are detected as individual or coeluting sets. We typically achieve 170 congener separations in environmental samples. Applying the primary calibration standard developed under Aim 1, samples are quantified by the internal standard method. Internal Standards and Surrogate Recovery Standards developed under Aim 1 are used to precisely determine PCB concentrations in samples. Methods for analysis on a congener-specific basis are assessed using performance standard injections and analysis of certified Standard Reference Materials. Most analyses are performed on the entire suite of PCB congeners, including laboratory animals exposed to the mixtures described in Aim 2 and including blood from humans and non-laboratory animals. Other samples are analyzed for specific congeners and metabolites in support of investigators focused on congener-specific toxicology. Specific Aim 4 involves the extraction, identification, and quantification of unknown metabolites. The Analytical Core determines purity of synthesized metabolites and associated analytical standards, then analyzes for hydroxylated PCBs and other PCB metabolites. As requested by the isbrp investigators, the Analytical Core will also train personnel and assist in sampling design and implementation. Specific Aim 5 is the design and maintenance of a database system. A redundant storage architecture with automatic backup and password protection is used to allow investigators to download data and reports produced by the Analytical Core.